bickford



(No Model.) 3 Sheets-Sheet 1.

J. H. BIOKFORD.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

No. 349,975. Patented Sept. 28, 1886.

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3 Sheets-Sheet 2.

(No Model.)

Patented Sept. 28, 1886.

Wilif'EEEEE n. PETERS. Phola-Lflhognphar, Washmgmn. D. C.

(No Model.) 3 Sheets-Sheet 3. J. H. BIOKFORD.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM. No. 349,975. Patented Sept. 28,1886..

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N PETERS, Pholn-Lllhogmpher, Wiihingmn, D. C.

UNTTED STATES ATENT FHQEQ JOHN H. BHKFORD, OF SALEM, MASSACHUSETTS,ASSIGNOR OF ON F-THIRD TO S. FRED SMITH, OF SAME PLACE.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

SPECKFICATION forming part of Letters Patent No. 349,975, datedSeptember 28, 1886.

Application filed NovcmbrrQS. 1885. Serial No. H3370. (No model.)

To all whom, it may concern.-

Be it known that I, JOHN H. BICKFORD, of Salem, county of Essex, andState of Massachusetts, have invented an-lmprovement in AutomaticTclephoneExchange Systems, of which the following description, inconnection with the accompanying drawings, is a specification, likeletters on the drawings representing like parts.

In telephone-exchange systems as now commonly constructed an operator isemployed to make connections and disconnections; but in small cities andvillages,where the number of subscribers is comparatively small, acentral office employing an operator cannot be maintained, and it hasbeen found desirable and commercially economical to construct a centraloffice which shall be automatically operatcd to connect and disconnectthe several subscribers lines one with another by thesubscribersindividually. Variousappliancesand systems have beenorganized in furtherance of this plan, and by my invention I seek toimprove and extend such plan,so as to render it more useful. \Vith thisobject in view I. have provided a central office containing a series ofnormally-groundcdinstrumentsoue instrument for each subscribci"s lineleading from the said central oflicesaid instruments comprising suitablemeans, which, when brought into cooperation, removes theground'terminals of the said instruments one by one at the will of thesubscriber, and also establishes a connection with such other instrumentas the subscriber may desire, the ground-terminal of the latterinstrument being the final one removed. The instruments at the centraloffice are each constructed substantially alike, are normally groundedand supplied with electro magnets in local circuits, saidelectromagnets, when energized, removing the normal groundterminals fromthe instruments. The instruments are interchangeably connected bymainline circuits,while the electro-magnets are also interchangeablyconnected with the said instruments by the local circuits. Theinstruments located at the central o'fliceone for each subscribersline-each consist of two fixed disks, each disk being composed ofinsulating material, and provided with a series of con ducting stops orsurfaces, preferably about its periphery, while between the said disks ashaft rotatesin suitable bearings, said shaft supporting two pens orcontact-pieces at opposite ends, which latter cooperate, respective] y,with the disks. The shaft also has mounted upon it a ratchet-wheel,which is moved step by step to rotate the shaft by a pawl fixed to aspringcontrolled armature of a polarized magnet. One of the disks ofeach instrument having the 6 series of conducting stops or surfaces,preferably upon its periphery, while cooperating with the traveling penor contact-piece, closes the local circuits, thereby operating suitableelectro-magnets therein, removing the normal ground-terminals from theremaining instruments, one at a time, while the other disk, also havinga series of conducting stops or surfaces, preferably upon its periphery,simultaneously cooperating with its traveling pen or contact-piece,connects the said instrument in circuit with the remaining instruments,one at a time, the subscriber controlling the movement of theratchetnvheel, thereby dctermining how many steps shall be taken. 7 Theinstruments at the central office are each numbered to correspond withthe line with whichitisiutimately connectcd,and the disks of eachinstrument are provided preferably with one normal or zero conductingstop or surface, and as many other conducting stops or sur faces asthere are instruments or subscribers lines leading from the centraloffice, the said conducting stops or surfaces of each disk beingnumbered alike and in rotation, commcnc- 8;, a

ing at the zero-stop, and the numbers or stops of each disk bearingcorresponding numbers are interchangeably connected by electric circuits. The conducting stops or surfaces of each instrument bearing itsown number, 0 counting from the normal or zero conductingstop,arealsonormallygrounded. Atthecentral office a main battery is alsolocated, onepole of which is normally grounded, while from the otherpole a battery-line leads beside a sub- 9 5 scribers line to thesubscribers stations. Each subscribcrs station is supplied with asuitable call or signal box, and such other appliances as may benecessary. The call-box consists of a break-wheel having a pen orcontact-piece connected with the battery-line, and arranged toco-operate therewith, but normally disconnected therefrom. Thebreak-wheel is set in motion by a motor, and its shaft is supplied witha pointer, the end of which normally rests upon a contact piece, boththe pointer and contact-piece being connected with the subscribers line.The break-wheel is preferably provided with as many notches or breaks asthere are subscribers lines, and its pointer swings overa dialhaving therespective numbers marked thereon. The box is also provided with fingersor stops, which when brought into position over or at a desired numberupon the dial limit the further rotation of the pointer, andconsequently the break-wheel will only rotate until the pointer strikesthe finger, remaining at rest until the finger or stop has been removedor returned to its normal position, when the break-wheel will continueand complete its rotation. When one of the stops or fingers is broughtinto position at a certain number and the motor started, the pointerleaves it contact-point, thereby opening the line behind it and rotatesuntil it strikes the said finger, there stopping while connection ismade with the subscribers instrument at the central office, and anotherinstrument bearing the number corresponding with the number marked uponthe dia at which point the finger is depressedgers or stops are pivotedat the call-box to a shaft, which latter is normally grounded, and

are supplied, whereby the fingers or stops at the call-box are returnedto their normal position after-a subscriber has finished hisconversation, which removal permits the pointer and break-wheel tocomplete their rotation, thereby, through the intervention of thepolarized magnet, completing the rotation of the shaft of theinstrument.

I have thus stated in a general way the salient features of this system,and I will now proceed to set forth and finally claim the es- I may,however, remark that, so far as I am aware,

sential features of my invention.

the polarized magnet, which is a very essential element of my system,has not heretofore been utilized in effecting the putting of subscribersautomatically into connection in such systems of telephony.

Figure 1 shows a diagram of subscribers lines leading to a centraloffice, a main battery in said central office, and battery-line; Fig. 2,a front elevation of one of the instruments located at the centraloffice with which the subscribers lines are connected; Figs. 3, 4,

and 5, details to be referred to; Fig. 6, a portion The tin-' of thecall or signal box, at the subscribers station, the face-plate beingremoved and the battery-line connected with the main battery at thecentral office, which latter is shown in diagram adjacent to thesubscribers station;

Fig. 7 a similar view to Fig. 6, the face-plate being added, also aportion of themagnetobell and the subscribers line; and Fig. 8,-a

diagram of the central office, showing three instruments, indicative ofthree subscribers lines and the arrangement of the circuits.

It is designed by this invention that several subscribers lines may leadfrom a central office and be interchangeably connected byautomatically-operated instruments at said central office, whereby thesubscriber upon one line may automatically make connection with anyother subscribers line leading from the central office. At the centraloffice a main battery, B, one pole of which is normally grounded, islocated, from which the batteryline leads to the several subscribersstations connecting with said central office, while the severalsubscribers lines converge at said central office, and by theintervention of suitable sulated from the shaft 1).

selecting-instruments are interchangeably connected. Each lineleading tothe central office is provided with a selecting-instrument (see Figs. 2,3, 4, and 5)which is normally grounded. The said selecting-instrumentsconsist of two fixed disks, (L a, connected with uprights of a suitableframe-work, as A. The disks a a are made of insulating material, and areprovided about their peripheries with conducting stops or surfaces, thedisk at having a single series, as at a while the disk a has a doubleseries, as at a a. The shaft b, mounted in suitable bearings in theuprights of the framework A, and between the disks a a, having rigidlyconnected therewith two pens or contact-pieces, b b", is rotatedintermitt-ingly by means of a ratchet-:wheel, c, fixed thereon, which-isengaged. by a pull-pawl, 0', connected with the spring-controlledarmature c of a polarized magnet, M, consisting of a permanent magnethaving soft-iron cores connected with the poles thereof and insulatedwire wound upon the cores. The pawl c is retained in engagement by aspring, 0 The pen I) is in- A retaining-pawl, 0*, is also provided toprevent the ratchet wheel from backward movement. As the shaft 2)rotates the pen or contact-piece I) wipes over the periphery of the diska, touching the conducting stops or surfaces thereon, whilesimultaneously the pen I)", provided with a bifurcated end, wipes overthe periphery of the disk a, and thereby touches both series ofconducting stops or surfaces thereon.

The selecting-instruments just described, and for convenience lettered0, located at the central office, and one for each subscribers line, areinterchangeably connected by the subscribers wires, which connect thedisks a of each instrument, the said wires being connected with theconducting stops or surfaces thereon, consequently each disk a isprovided with as many conducting-stops a as there are subscribers lines,and also with one additional conducting-stop, upon which the pen I)norinally rests, which may be called zero. Each selecting-instrument isnumbered to correspond with the number of the subscribers line withwhich it is intimately connected, as, for instance, referring to Figs. 1and 8, the subscribers lines 1 2 3 connect intimately with theselecting-instruments 1 2 3, respectively, and the conducting-stops uponthe disk a of the several instruments 1 2 3 will each be characterizedby the numbers commencing at zero, as, forinstance, the nextconducting-stop after zero of each disk at will be numbered 1, whichupon instrument No. 1 will be its own number, while upon instrument No.2 will be the conductingstop with which instrument No. 1 is connectedwith No. 2, and so on, while conducting-stop No. 2 upon instrument No.lwill be connected with instrument No. 2, and conducting-stop No. 2 uponinstrument No. 2 will be its own number, as clearly shown in Fig. 8. Ateach instrument the conductingstop upon the disk a bearing the number ofthe instrumentitself is grounded at G, for purposes hereinafterexplained. The disk a of each instrument is provided with a doubleseries of conducting-stops, a" a", there being as many pairs as thereare conducting-stops a" upon the disk a, and arranged at equal distancesapart, so that the pens I) Z), travel ing by means of the shaft 1),simultaneously touch their conducting-stops. The disk c of eachinstrument is arranged similar to the disk a, in that it has azero-point, and the pairs of conducting stops are numbered, countingfrom zero, the same as the conducting-stops upon the disk a. Local.circuits containing batteries F, and electro-magnets m, operatingspring-controlled armatures m, which latter control the normalground-terminals of each instrument, are connected interchangeably withthe several pairs of conducting-stops upon the disks cof eachinstrument, similar to the subscribers lineconnections upon the disk a,that pair of conducting-stops of each disk a bearing its own numberhaving no connection whatever, while the zero point or points over whichthe pens I) normally rest are insulated. As before stated, the severalsubscribers lines lead from the central office, and the subcribersstations are looped into the said lines, while a battery-line leads fromthe main battery 1- also located at the central oifice besidethesubscribers lines, and each subscribers station is also connected withsaid battery-line.

Referring to Figs. (3 and 7, the call or signal box by meansof which theinstruments at the central office are automatically operated are shown,together with a portion of a magneto-bell, and it is obvious that suchother applianees as commonly found at atelephone subscribers station maybe located here also, and suitably connected in circuit, although notshown. Each call-box is provided with a break-wheel, D, set in motion,when desired, by any suitable motor and train of wheel work. The pen (I,connected with the batteryline, is arranged to co-operate with thebreakwheel I), but is normally disengaged therefrom. A pointer, 1), isplaced upon the shaft of the breakwheel 1), one end of which isconnected with the wire 10, being a portion of the subscribers line,while its opposite end normally rests upon the contaetstud s, which isconnected with another portion, 12, of the subscribers line, so thatwhen the pointer is at rest the current will pass through the wire 12,poinlerp, and wire 10, thereby permitting any other box located in thesame subscribers line behind it to transmitits signal.

Fig. 7 represents the box shown in Fig. 6, and the mechanism by which itis connected with the magneto-bell N, the main battery at the centralstation being shown adjacent to the box to more clearly illustrate theoperation. The brealewheel D is supplied with as many notches as thereare subscribers lines, or as there are instruments at the centraloffice, and rotation of the break-wheel D connects the battery line withthe subscribers line, and thereby sends an impulse to the centralol'lice for each notch or closure.which will depolarize the polarizedmagnet M, releasing its armature c,and thereby permitting the latter,aided by the force of the spring 50, to engage the next tooth oftheratchetwheel c, the openin of the line by means ofthe break-whcel 1) pelinitting the magnet M to again attract its armature, and thereby pullthe ratchetwheel cone tooth, and, as the ratchetwheel c is toothed toalso correspond with the number of subscribers lines, a completestep-by-step process is carried out. Stops or lingers aone for eachsubscriberslineare connected with a rod, 12, at each eall-box,andarceapablcofbei ngturned down into the path of rotation of the pointer p,to thereby stop the pointer p at that point. These stops or fingers arearranged at suitable distances apart correspomling with the notches ofthebreak-wheel l),so as to retain the pointer p, and consequentlythebreak-wheel D, at any desired pointal'ter it has caused a determinednumberof impulses to be transmitted, the pen or contact-piece (l 'at thetime the pointer strikes the linger or stop a being disengaged. The roda isnormally grounded at G, 161' purposes to be hereinafter explained,and when the pointer strikes a certain fingeror stop,11,the subscriberslineis broken at the contact-stud 8, while the circuit from the ground Gpasses through the rod a, fingera, pointer 1), over the subscribers line10. Each subscribers line leading from the central ollice terminates ina groundconnect-ion, as shown, in Fig. 1. After the pointer 1) has beenretained by one of the lingers or stops at a sufficient length of timetoallow the subscriber to complete his conversation the subscriber hangshis telephone upon the lever r of the magneto-bell N, which draws theconnecting-rod f downward, thereby rotating the crank f, turningtheshaft f ICC) which latter is provided with a flat strip,f", whichstrikes the fingers or stops at and returns them to their normalposition, thereby permitting the pointer and its break-wheel D tocompleteits rotation.

The operation is as follows: Normally the circuit is from the main orsubscribers line through the magnet M, shaft b, pen thence by wire 20through the armature m to the ground. Should the subscriber upon lineNo. 1 desire to make connection with a subscriber upon line 3, he firstdepresses the finger or stop n, pointing to Fig. 3, marked upon the faceof the call-box, then starts his motor, and the pointer travels forwarduntil it strikes thefinger, when it comes to rest. In the meantime thebreak-wheel D is rotated sufficiently to cause the pin (Z to connect thebattery-line with the subscribers line'three times, thereby sendingthree impulses. The impulses thus transmitted from the subscribersstation are of opposite polarity to the polarized magnet M, therebydepolarizing it, repelling the armature, while the signalcurrent comingfrom any subscriber passes through the polarized magnet in a reversedirection, and being of the same polarity merely acts to attract thearmature still stronger. Upon transmitting the first impulse thepolarized magnet M by its pawl draws the ratchet-wheel 0 one tooth,thereby rotating the shaft b sufficiently to cause the pens b b to comein contact with the conducting stops or surfaces N0. 1, which being thenumber of the instrument, the current will pass from the subscribersline through the magnet M, shaft I), pen I), and thence to the ground G,the pen b", as previously stated,being preferably insulated from theshaft b. The second impulse causes the polarized magnet M to move theratchet-wheel 0 another tooth, and thereby the pens I) b to come incontact with the conducting stops or surfaces No. 2, the current at thistime passing from the subscribers line through the shaft and pen I) ofthe said instrument, the pen b closing the local circuit, therebypermitting the current to pass through the wires 22 23 24 25, cansingthe magnet m to attract its armature and thereby remove theground-terminal from the instrument No. 2, while the current leaving thepen I) of the first instrument will pass through the wires 26 27 28 29,pen I) of instrument No. 2, its shaft, and thence reversely through thepolarized magnet M to the subscribers line No. 2, and the third impulsewill cause a similar operation and connection of circuits at instrumentNo. 3 as the second impulse caused at instrument No. 2. Should thesubscriber upon line No. 2 want to connect with subscribers lineNo. 1,the operation will be similar to that just described, the break-wheelrotating one notch, at which time the pointer will strike the finger No.1, when the current will pass over subscribers line 2, throughinstrument No. 2, its pen b bearing upon the conducting-stop No. 1',

closing the local circuit, thereby removing the gronnd;terminal frominstrumentNo. 1, and the current leaving the pen I) of instrument No. 2will pass over the wire 30 31 32 20: through the penb of instrument No.1, its shaft, and thence reversely through the polarized magnet M to thesubscribers line No. 1. After the subscriber has completed hisconversation he hangs the telephone upon the lever r of themagneto-bell, which, as previousl y described, returns the fingers orstops a to their normal positions, thereby releasing 1 the pointer,which then completes its rotation,

and through the intervention of the polarized magnet M at the centraloffice causes the selecting-instrument to return toits normal positionstep by step. As will be readily seen,

the callbox at the station desiring to communicate being grounded, whenthe desired connection is made behind the magneto-bell, and otherappliances a ground wire is completed over which conversation may becarried on.

I claim- 1. In a telephone-exchange system, the combination,substantially as herein set forth, of

a series of subscribers lines converging at a 1 main or central station,a selecting-instrument,

1 contact piece or pen, and means, substantially as described, foroperating said mechanism fro m. a distance.

2. i In a telephoneexchange system, the combination, substantially ashereinbefore set forth, of a series of subscribers lines converging at acentral or main ofilce, a selecting-instrument, substanti ally asdescribed, including a polarized magnet for each subscribers line andlocated at the central office, said select- I ing-instrument containinga series of conducting stops or surfaces, a co-operating movable contactpiece or pen and actuating-motor therefor for causing the contactpieceor pen to make connection with the said conducting stops or surfacesconsecutively, said contact-piece normally resting upon a groundedconductingstop, while the remaining conducting-stops are interchangeablyconnected with corresponding conductingstops of the severalselectinginstruments, with the exception of that conducting-stop whichis characterized by the number of the selecting-instrument of which itforms a component part, which latter is grounded.

3. In a telephoneexchange system, the combination, substantially ashereinbefore set forth, of a series of subscribers lines converging at acentral or main office, a selectinginstrument, substantially asdescribed, for each subscribers line, and located at the central office,said seleeting-instrument containing a series of conducting stops orsurfaces, a cooperating movable contact piece or pen and actuating-motortherefor, for causing the contact piece or pen to make connection withthe said conducting stops or surfaces consecutively, said contact-piecenormally resting upon a grounded conducting stop, while the remainingconductingstops are interchangeably connected with correspondingconductingstops of the several selecting-instruments, with the exceptionof that conducting stop which is characterized by the number of theselectinginstrument, of which it forms a component part,which latter isgrounded; also a series of pairs of conducting stops or surfacescorrespondinglyloeated with the former series of conducting-stops, thosetwo pairs corresponding with the two grounded conductingstops beingomitted, a local circuit connected with each remaining pair, and acontact piece or pen and actuating-motor therefor moved simultaneouslywith the contact-piece above mentioned, and arranged to make connectionwith the several pairs of conducting-stops consecutively, but normallydisengaged therefrom, electromagncts in said local circuits andoperating to remove the normal ground-terminal from the first mentionedcontact-piece.

4. In a telephone-exchange system, the combination, substantially ashereinbefore set forth, of a series of subscribers lines converg ing ata central office, a normally-grounded selecting instrument,substantially as described, for each subscribers line, located at thecentral office, and interchangeably connected with each other, a movablecontact piece or pen forming a co-operative part of theselect-irig-instrument, a shaft, to which said contact-piece isattached, a ratchet-wheel, and pawl for rotating the ratchet-wheel, anda polarized magnet controllingthe operation of the said pawl and formingpart of each selectinginstrument.

5. In a telcphoneexchange system, the combination, substantially ashereinbefore set forth, of a series of subscribers lines converging at acentral or main office, a normallygrounded selecting-instrument.substantially as described,for each suhscribeflsline, located at thecentral office, and interchangeably e011- nected with each other, amovable contact-piece for each seleeting-instrument, and a rotary shaftcarrying such contact-piece, a ratchet on said shaft, and a pawlco-operating therewith, and controlled by a polarized magnet, forintermittingly moving the said contact-piece to establish electricalconnection between different pairs of the said selecting-instruments,andoperating simultaneously with the said contact-piece for removing theground-terminals from the several selectinginstruments eonsecutively.

6. In a telephone-exchange system,thecombination, substantially ashereinbefore set forth, of a series of subscribers lines converging at acentral or main office, a normallymoving eontactpiece under the controlof a polarized magnet for establishing electrical connection betweendifferent pairs of Selectinginstruments, a call or signal box at thesubscribers station, containing a break-wheel and cooperating pen forcontrolling the movement of thepolarized magnet, and means,substantially as described, for stoppingthebreakwheel at anypredetermined point during its rotation for an interval of time.

7. In an electric circuit, acall or signal box containing a motor,break-wheel, and co-opcrating pen or contact-piece normally disengagedtherefrom, and connected with the battery-line, a pointer mounted uponthe break wheel shaft,which latter is connected with the main line, acontact-stud, also connected with the main line, and upon which thepointer normally bears, aseries of normally-grounded stops, 11, arrangedto be brought independehtly into the path of rotation of the saidpointer, and against which the pointer strikes when rotated by thebreak-wheel, thereby determinin g at will the number of impulsestransmitted by the break-wheel breaking the line behind the box andgrounding the main line.

8. In an electric circuit, a call or signal boX containing a motor,break-wheel, and co-operating pen or contact-piece normally disengagedtherefrom and connected with the battery-line, a pointer mounted uponthe breakwheel shaft, which latter is connected with the main line, acontact-stud, also connected with the main line, and upon which thepointer normally bears, a series of normally -grounded stops, a,arranged to be brought independently into the path of rotation of thesaid pointer, and against which the pointer strikes when rotated by thebreak-wheel, thereby determining at will the number of impulsestransmitted by the break-wheel, breaking the line he hind the box andgrounding the main line, and means, substantially as described, forantomatically restoring the stop a to its normal position, permittingthe break-wheel to complete its rotation.

9. An instrument for governing the transmission of an electric currentover severalnormally grounded subscribers lines consecutively, whichconsists of a disk, a, having ase ries of conducting stops or surfacesabout its periphery, a pen, I), and rotating shaft b, said pen normallyresting upon that conductingstop through which the main-line isgrounded, while the remaining conducting-stops are independentlyconnected with the lines having the ground-terminals, a disk, 0/, havinga se ries of pairs of eomlucting-stops about its periphery, a pen, I),having a bifurcated end and attached to but insulated from the saidrotating shaft b, thereby moving sinuiltancously with the pen I), thesaid pen I)" normally resting upon an insulated portion of the disk a,

whilethe several pairs of conducting-stops are connected with localcircuits containing local batteries and electromagnets, which, whenoperated, remove the normal ground-terminal at one end of the severalsubscribers lines consecutively, aratchetwheel, c, and pawl c, andmeans, substantially as described, for intermittingl y moving the saidpawl, all as set forth.

10. In a system for telephonic communication, a series of subscriberslines leading to a central office, and having normal ground-terminals, aselecting-instrument, substantially as described,for each subscribersline, located at the central office, and interchangeably connected witheach other, means, vsubstantially as described, intermittinglycontrolled by a polarized magnet, for establishing electrical connectionwith each of the several selectinginstruments consecutively andsimultaneously removing the ground-terminals of each .subscribers lineat the central office consecutively, commencing with instrument No. 1.,and following in rotation until a desired number is reached, a call orsignal box at each subscribers station containing a break-wheel,and

cooperating contactvpiece or pen normally, disengaged therefrom, andconnected in circuit with amain battery, the break-wheel having as manynotches as there are subscribers lines, a pointermounted upon thebrealcwheel shaft, which latter is connected with the subscriber s line,while the pointer normally bears upon a contact-stud, also connectedwith the subscribers line, and means, substantially as described, undercontrol of the subscriber,for stopping the rotation of the break-wheelat any desired point for a period of time, and grounding the subscribersline at the box in which the break-wheel is rotating, therebycontrolling the intermittent operation of the polarized magnet andreleasing mechanism for the break-wheel, that it may complete itsrotation, all substantially as described.

In testimony whereofl have signed my name to this specification in thepresence of two subscribing witnesses.

JOHN H. BIQKFORD.

Witnesses:

D. \V. GoocH, J. H. CHURCHILL.

